Various types of rectifier units, including among others, rectifier units for motor vehicle alternators, are known. In the known generators that are made in cylindrical shape, the rectifier units have been provided in the general form of a circular disk, usually with a central opening for the alternator shaft.
One of the known rectifier units is described in German published patent application (AS) 1,916,237, in which the positive-side diodes are mounted on one cooling body of the form of a cooling plate and the negative-side diodes are mounted on another such cooling body, the cooling plates taking the shape of an inner and an outer concentric sheet metal ring, both affixed to an insulating plate provided for carrying electrical connection elements.
U.S. Pat. No. 3,789,285 and the corresponding German published patent application (AS) 2,247,627 disclose a rectifier unit in which cooling plates are provided in the shape of circular sectors, one carrying the positive-side diodes and the other the negative-side diodes, the cooling plates being affixed to an insulating plate carrying the necessary connection conductors. The connecting up of the diodes in this case is provided by a patterned metal sheet that is cast into the insulating plate.
Finally, German Pat. No. 2,250,557 discloses a rectifier unit in which the positive-side diodes in one case and the negative-side diodes in another are each fastened to an annular disk-shaped cooling plate, the two plates being superimposed and insulated in sandwich construction and each having at its ends claw-shaped extensions.
These known rectifier units have the common disadvantage that the positive-side diodes are arranged on one cooling plate and the negative-side diodes on another, while the exciter field diodes are in every one of these constructions separate and must be soldered on the insulatingly affixed conductor plate. This requires an additional sequence of operations in manufacture and also involves risk of disturbances in operation, since under vibration and shaking of the generator the exciter field diodes can become loose from the insulating plate that carries the circuit.
Furthermore, in the case of alternators of higher ratings, substantial quantities of heat must be dissipated even from the excitor field diodes. It has therefore been proposed for alternators of higher ratings, for example in utility vehicles, to provide multiple cooling body systems in which an individual cooling body is provided for the exciter field diodes, which can be provided, for example, by a light metal injection molding.